Beginner user of R here struggling with a repeated measures ANOVA.
I have a dataset that consists of one between subjects factor with 4 levels (coded in a single variable called 'groups'), and one within subjects factor with 4 levels (coded in four separate variables 'DV1', 'DV2', 'DV3', 'DV4').
I have the following objectives:
- Run an overall repeated measures ANOVA.
- Compare groups using custom contrasts (as in an LMATRIX command in SPSS).
- Compare different levels of DV using custom contrasts (as in an MMATRIX command in SPSS).
- Do a combination of 2) and 3) simultaneously so I am comparing only certain groups at certain levels of the within-subjects factor.
- Run a set of contrasts that do NOT sum to zero.
I know I can do this in SPSS without much of a problem, but I can't get a clear idea of how to do this in R. I've seen how parts of this could work in different packages, but I have not so far seen how this could work within one procedure or a set of related procedures in R.